The streets of 1920s Paris are teeming with tourists and tramps, fine artists and con artists. Also killers. Knife fights at cafés and corpses floating along the Seine are all part of the daily parade. But now something newly wicked is in the air—murder with style. A day at the Louvre might reveal a fresh body among the dusty corpses of Egyptian nobles. Josephine Baker’s dazzling performance at the Théâtre des Champs-Élysées could be the scene of an unexpectedly dramatic tragedy. Passionate Paris is indeed a perilous place in Barbara Cleverly’s recent mystery, Folly du Jour.